Colorants have heretofore been used as dyes or pigments, but with the progress of electronics technologies, they are increasingly used in various fields as key materials for information display and data recording systems. Accordingly, colorants are required to have various abilities, and the development of colorants having physical and functional properties suitable for many applications is demanded.
With respect to fluorescent colorants, high luminescence intensities, and appropriate optical absorption wavelengths and luminescence wavelengths are desired. Further, it is desired for fluorescent colorants to emit light, not only in solution but also in the solid state (this property is hereinafter referred to as “solid-state luminescence”), and to have excellent performance in terms of heat resistance, light resistance, solubility, dispersibility in resist materials, etc.